When to choke a 912ULS

[3kdscf]

Just curious, when do you use the choke to start your 912ULS? The manual says:

"If engine in operating temperature, then start the engine without choke" (operator manual page 3-7)

I live in the desert where its often 90-110F on a "cold start". I was using the choke as instructed since the temperature was not up to the operating range but I was finding the starting was not as smooth and easy as it should be in a rotax. It even flooded once rather than starting. I then stopped using the choke on a cold start when the air temp is above 90F and its started smoothly every time since. Has anyone else noticed this? At what air temperature do you stop using your choke for a cold start?

[ScottS97385]

The "choke" on a 912 equipped with Bings is not anything like the carb chokes of old, there is no butterfly to close. Instead of pulling the knob clear out try using 1/4-1/2 or less of the open position on warmer days.







Just curious, when do you use the choke to start your 912ULS? The manual says:

"If engine in operating temperature, then start the engine without choke" (operator manual page 3-7)

I live in the desert where its often 90-110F on a "cold start". I was using the choke as instructed since the temperature was not up to the operating range but I was finding the starting was not as smooth and easy as it should be in a rotax. It even flooded once rather than starting. I then stopped using the choke on a cold start when the air temp is above 90F and its started smoothly every time since. Has anyone else noticed this? At what air temperature do you stop using your choke for a cold start?

[3kdscf]

The "choke" on a 912 equipped with Bings is not anything like the carb chokes of old, there is no butterfly to close. Instead of pulling the knob clear out try using 1/4-1/2 or less of the open position on warmer days.

Thanks. Was not aware that you could partially engage the choke but it makes sense with the V shape of the opening.

[Av8r3400]

The "choke" is an enrichening circuit internal to the carburetors on a Bing 64.

It is not a proportional valve. It either opens or closes a circuit allowing more fuel to pass into the throat of the carburetor when the throttle is less than 10% open.

If you are having hard starting issues, often narrowing the gap on the spark plugs from .7mm (.0275") to .5mm (.020") can help this.

[ScottS97385]

The "choke" is an enrichening circuit internal to the carburetors on a Bing 64.

It is not a proportional valve. It either opens or closes a circuit allowing more fuel to pass into the throat of the carburetor when the throttle is less than 10% open.

If you are having hard starting issues, often narrowing the gap on the spark plugs from .7mm (.0275") to .5mm (.020") can help this.

I beg to differ on the valve not being proportional, I slowly push the tee knob in(mine is the locking type) as the engine warms.

[skyguy04]

I understand what Mangy is saying. If you look at how the starting circuit works, there are tiny holes that, when the "choke" is engaged, air is re-directed through a completely different pathway with it's own air fuel mixing. It would seem that the only way air flow, knowing it likes the path of least resistance, could be directed through this alternate pathway is for the choke to be fully engaged. That being said, I too have experienced a proportionate improvement in engine smoothness as i push the choke back in. I have never intentionally moved the control slowly though. I will try that the next time i fly and see what happens.